1. Field of the Invention
The present invention relates to an analog-to-digital converter, and more particularly, to a flash analog-to-digital converter.
2. Description of the Related Art
A conventional n-bit one-channel flash analog-to-digital converter is comprised of 2.sup.n (here, n is a positive integer) resisters and (2.sup.n -1) comparators. In such a flash analog-to-digital converter including many comparators and resisters, in order to achieve linearity of the converter, it is important to make the properties of the comparators and resistors consistent with one another.
However, due to process variations, a property mismatching problem may occur so that the properties of the comparators or the resistors are different from one another. When the property mismatching problem exists, linearity of the analog-to-digital converter is degraded, and malfunction or erroneous conversion may occur. Thus, it is generally difficult to employ the flash analog-to-digital converter for an application which requires analog signal conversion to high precision such as 6 bits or more.
Meanwhile, with a recent trend toward multichannel signal processing, a number of analog-to-digital converters, corresponding to the number of channels, are simultaneously used. However, when many flash analog-to-digital converters are simultaneously used, the property mismatching between the analog-to-digital converters of different channels may also occur.